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How does a relational database work?

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Re: How does a relational database work?

#5

Post by jlees »

This is also a pretty accessible quick intro to complexity and data structures, nicely done. Definitely the sort of thing I would include as further reading in a beginner course -- some beginners love to understand "why" and this post answers pretty much all the "why" possible.

Re: How does a relational database work?

#6

Post by mgachka »

mgrennan wrote: post #4

Not that Cassandra and Hadoop don't have a place. But because NO-SQL is hot I see lots of young coders (I'm and old DBA) try to turn document store systems into relational databases. They should all be made to read this post.

(I'm the author of the article) I'm 28 and I’m currently a Big Data developer (I use Hadoop, HBase, Hive …) and I don’t understand the buzz surrounding Big Data and NoSQL.

With a relational database the complexity is hidden (more or less…) whereas with Big Data and NoSQL the developer needs to deal with this complexity himself/herself. As a result, most of the Big Data applications I’ve seen don’t work well.

A really like Big Data because it’s more complex but to be honest, most of the time my work does not required the “Big Data scale”.

Re: How does a relational database work?

#7

Post by jandrewrogers »

Good overview of traditional OLTP architectures. As complicated as they look from the article, it is just scratching the surface of a sophisticated implementation. There are many internals common to more advanced designs that are not even mentioned, and the article is already quite long!

The thing I love most about database engines is that there is probably more hardcore computer science per line of code than any other software system of similar scope. It is a very rich ecosystem for an algorithms and data structures geek.

Re: How does a relational database work?

#8

Post by jchrisa »

mgachka wrote: post #6
mgrennan wrote: post #4

Not that Cassandra and Hadoop don't have a place. But because NO-SQL is hot I see lots of young coders (I'm and old DBA) try to turn document store systems into relational databases. They should all be made to read this post.

(I'm the author of the article) I'm 28 and I’m currently a Big Data developer (I use Hadoop, HBase, Hive …) and I don’t understand the buzz surrounding Big Data and NoSQL. With a relational database the complexity is hidden (more or less…) whereas with Big Data and NoSQL the developer needs to deal with this complexity himself/herself. As a result, most of the Big Data applications I’ve seen don’t work well. A really…

At Couchbase we did a survey of developers (this was ages ago) and the biggest motivator for NoSQL was schema flexibility. Not having to coordinate migrations is seen as a productivity boost. [1]

The other thing document databases can offer that relational databases struggle with is taking subsets (which we use for offline sync.) [2]

[1] http://blog.couchbase.com/nosql-adoption-survey-surprises

[2] http://developer.couchbase.com/mobile/

Re: How does a relational database work?

#9

Post by kodablah »

mgachka wrote: post #6
mgrennan wrote: post #4

Not that Cassandra and Hadoop don't have a place. But because NO-SQL is hot I see lots of young coders (I'm and old DBA) try to turn document store systems into relational databases. They should all be made to read this post.

(I'm the author of the article) I'm 28 and I’m currently a Big Data developer (I use Hadoop, HBase, Hive …) and I don’t understand the buzz surrounding Big Data and NoSQL. With a relational database the complexity is hidden (more or less…) whereas with Big Data and NoSQL the developer needs to deal with this complexity himself/herself. As a result, most of the Big Data applications I’ve seen don’t work well. A really…

"With a relational database the complexity is hidden"

That is my main issue. I use Cassandra over relational firstly for its linear scalability and multi-master-esque HA. But even ignoring those, I understand exactly what is being scanned and what is not, I don't have to fight with an optimizer at runtime based on several parameters.

Re: How does a relational database work?

#10

Post by somedudethere »

jchrisa wrote: post #8
mgachka wrote: post #6

Earlier quoted context omitted.

(I'm the author of the article) I'm 28 and I’m currently a Big Data developer (I use Hadoop, HBase, Hive …) and I don’t understand the buzz surrounding Big Data and NoSQL. With a relational database the complexity is hidden (more or less…) whereas with Big Data and NoSQL the developer needs to deal with this complexity himself/herself. As a result, most of the Big Data applications I’ve seen don’t work well. A really…

At Couchbase we did a survey of developers (this was ages ago) and the biggest motivator for NoSQL was schema flexibility. Not having to coordinate migrations is seen as a productivity boost. [1] The other thing document databases can offer that relational databases struggle with is taking subsets (which we use for offline sync.) [2] [1] http://blog.couchbase.com/nosql-adoption-survey-surprises [2] http://developer.c…

I'm in the opposite camp. I don't like NoSQL because of the flexible schema. I have to build tools to make sure my data is consistent or have error handling. Migrations ensure that whenever I pull down a version of the code, the database is in the right state.

I don't see too many use cases where having being schemaless is a good thing outside of infrastructure ease of use. If you want to store arbitrary data in a table, BJSON in postgres is very efficient and flexible in that regard, while allowing you to have a schema for the rest of the data (e.g. if you are collecting data you probably want a schema for things like name, email, timestamp, etc and then have a BJSON field to jam in whatever you need.)

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